Light steel keel connecting structure

ABSTRACT

A light steel keel connecting structure, comprising at least two light steel keels, each of which has a connecting surface connecting with the other light steel keel, and connecting pieces for connecting the light steel keels, characterized in that concaves are provided on each of the connecting surfaces respectively which are depressed toward inside of the light steel keels, and the concaves of two connecting surfaces which are connected vertically are disposed by way of embedding, and at least two connecting holes are provided at corresponding positions of two concaves that are embedded, respectively, and the connecting pieces are provided within the connecting holes in a state of connection. The terminals of the connecting pieces at one end where depression sides of the concaves are located do not go beyond outer edges of the openings of the concaves on the same side as the terminals of the connecting pieces. At the junction of the light steel keel connecting structure of the invention, there is provided, a concave structure, for which, a mechanized mass production can be implemented very easily. The positioning is extremely easy during assembling, because concave structures of upper and lower connecting surfaces are engaged with each other. Strength of connection and rigidity of light steel keels are greatly improved. Top surfaces of connecting pieces can be wholly submerged in the concave, and accordingly, they will not cause interference to other connecting components on surfaces of the light steel keels.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a steel structure for construction use,and particularly, to a connecting structure of light steel keels.

2. Description of the Related Art

With the rapid development of building industry, new constructionmaterials continue to emerge, and light steel keel as a new constructionmaterial has been more and more widely used in various buildingstructures because of its excellent properties of light weight, highstrength, waterproof, fireproof, earthquake-proof installation and useconvenience, and so on. In the course of constructing a structure withlight steel keel, different light steel keels generally need to beconnected with one another, and what is usually used for the connectionis such a manner as welding, bolt connection or riveting.

Considering the current situation of light steel application, it isnecessary that a connecting structure for connection of the light steelkeels meet certain requirements: {circle around (1)} requirements onstrength, such as, as static strength, a fatigue strength, etc.; {circlearound (2)} size requirements, such as, requirements on the centerdistance between screws, bolts or rivets and the distance from a singlecenter to any side; {circle around (3)} stiffness requirements, forexample, requirements on rigidity of the structure which should bestrong enough so that a deformation upon resistance to an external loadshould be small enough not to cause cracking and breakage of aconstruction material attached thereto, such as a gypsum board; {circlearound (4)} process requirements, such as easy and simple processing,reliable operation and stable quality; {circle around (5)} andfurthermore, from the perspective of structural design, requirements onmaterial cost advantages such as reduced material weight and loweredmaterial cost, resulted from the design of such a connecting structure.

By adopting a welding connection, although the above requirements instrength, size and stiffness can be met, this connecting manner is anundetachable connection, such that the recyclability of material ispoor, the operation is relatively complex and the pollution toenvironment is relatively large. Therefore, what is comparatively commonis that a detachable connecting manner of bolt connection or riveting isadopted all the same.

In order to allow the connecting structure of light steel keels, whichadopts a detachable connecting manner, to meet the above strengthrequirements of connection, increasing the diameter of connecting pieceswill generally be taken into consideration. However, because thethickness of steel products used for the light steel keels is thin, andthe connecting structure has to meet the above size requirements aswell, the diameter of the connecting pieces used such as screws, bolts,rivets or the like may not be made too large. Thus, it is impossiblethat very high requirements on strength are met by the connectingstructure with the use of this method.

And, an existing light steel keel connecting structure that adopts adetachable connecting manner cannot reach very good stiffnessrequirements, either, and detailed explanation is as follows. A typicalstructure of light steel wall is shown in FIG. 1, in which, a figure onthe left side shows the structure of light steel wall in a normalcondition where no force acts on it, and a figure on the right sideshows the structure of light steel wall after it is deformed by a force.As can he seen from FIG. 1, in the event that an existing connectingstructure is employed, although there is also a diagonal bracingstructure for reinforcing the rigidity of the structure, the structurewill be deformed along a diagonal direction in the plane as well, andthis kind of deformation will be very obvious upon assembling of thestructure. That is, in the figure on the left side, if a fixedconstraint is applied to a point B, and a lateral thrust is applied to apoint D, then as can be seen from the figure on the right side,deformation of the structure is very obvious in this case. Taking alight steel wall with a size of 2800 (height)×3800 mm (width) as anexample, when a load of 40 KG is applied to the point D, the differencein length between diagonal lines AC and BD will reach 60 mm (while thedifference between the diagonal lines in case of no deformation is 0),and this deformation tends to bring about damage to the structure itselfand to the decoration materials attached to light steel, such as agypsum board.

Also, because an existing light steel keel connecting structure cannotreach very high strength and stillness requirements, it is usuallynecessary to increase the arranging density of light steel keels of alight steel assembly so as to ensure stability of the assembly when theconnecting structure is in use. In such a way, the above requirements ofdecreasing, the material weight and reducing the material cost, whichneeds to be met by the connecting structure, may not be met favorably.

SUMMARY OF THE INVENTION

The main purpose of the invention is to solve such a technical problemsuffered by a light steel keel connecting structure in prior art that,strength of connection and rigidity of the structure are not high andthe material weight of an assembly that employs the connecting structureis hard to decrease to reduce the material cost.

For solving the above technical problem, the invention provides a lightsteel keel connecting structure comprising at least two light steelkeels, each of which has a connecting surface connecting with the otherlight steel keel, and connecting pieces for connecting the light steelkeels, characterized in that concaves are provided on each of theconnecting surfaces respectively which are depressed toward inside ofthe light steel keels, and the concaves of two connecting surfaces whichare connected vertically are disposed by way of embedding, and at leasttwo connecting holes are provided at corresponding positions of twoconcaves that are embedded, respectively, and the connecting pieces areprovided within the connecting holes in a state of connection.

In the light steel keel connecting structure, the terminals of theconnecting pieces at one end where depression sides of the concaves arelocated do not go beyond outer edges of the openings of the concaves onthe same side as the terminals of the connecting pieces.

In the light steel keel connecting structure, the center distancebetween any two adjacent connecting pieces is not smaller than threetimes of the diameter of the connecting pieces, and the distance fromthe center of any of the connecting pieces to any of the outer edges ofthe light steel keels is not smaller than one and half times of thediameter of the connecting pieces.

In the light steel keel connecting structure, the openings of theconcaves are slightly larger than bottom surfaces, and the connectingholes are provided on the bottom surfaces of the concaves.

In the light steel keel connecting structure, the shapes of bottomsurfaces of the two concaves that are embedded vertically are shapes ofcircle, cross, square, rectangle, or ring, which match to each othervertically.

In the light steel keel connecting structure, the light steel keelscomprise a main light steel keel and at least one abutting light steelkeel, which are connected to each other, each of the main light steelkeel and the abutting light steel keel comprises an upper wing plate anda lower wing plate that are disposed horizontally and in parallel, and aweb connected vertically between one side of the upper wing plate andone side of the lower wing plate, the concaves are disposed at locationwhere the upper wing plate of the main light steel keel and the upperwing plate of the abutting light steel keel are connected and atlocation where the lower wing plate of the main light steel keel and thelower wing plate of the abutting light steel keel are connected, andconcaves on the upper and lower wing plates of the main light steel keelare embedded inside concaves on the upper and lower wing plates of theabutting light steel keel, respectively.

In the light steel keel connecting structure, the number of the abuttinglight steel keel is one, the upper and lower wing plates of the mainlight steel keel are provided one said concave in symmetric positions ofthe upper and lower wing plates of the main light steel keel,respectively, the upper and lower wing plates of the abutting lightsteel keel are also provided one said concave in symmetric positions ofthe upper and lower wing plates of the abutting light steel keel,respectively.

In the light steel keel connecting structure, the number of the abuttinglight steel keel is two or more, and the upper and lower wing plates ofthe main light steel keel are provided with concaves arranged in a linein symmetric positions of the upper and lower wing plates of the mainlight steel keel, respectively, the number of cavities is equal to thenumber of the abutting light steel keel, and the upper and lower wingplates of each abutting light steel keel is provided with one of saidconcave in symmetric positions of the upper and lower wing plates ofeach abutting light steel keel, respectively.

In the light steel keel connecting structure, the concaves are disposedin the middle part of the upper and lower wing plates of the main lightsteel keel, one end of the upper wing plate of the abutting light steelkeel and one end of the lower wing plate of the abutting light steelkeel, and the main light steel keel is connected to one end of theabutting light steel keel.

In the light steel keel connecting structure, the concaves are disposedin the middle part of the upper and lower wing plates of the main lightsteel keel and in the middle part of the upper and lower wing plates ofthe abutting light steel keel, the abutting light steel keel penetratesthrough the web of the main light steel keel vertically, and the middlepart of the main light steel keel and the middle part of the abuttinglight steel keel are connected in the state of penetrating throughvertically.

The present invention possesses the following beneficial effects. At thejunction of the light steel keel connecting structure of the invention,there is provided a concave structure, for which, a mechanized massproduction can he implemented very easily.

The positioning is extremely easy during assembling because concavestructures of upper and lower connecting surfaces are engaged with eachother. Besides, two connecting pieces or more can be accommodated withinthe concave structure, so that strength of connection and rigidity oflight steel keels are greatly improved as well. A load will be shared byconnecting pieces because two connecting pieces or more are used forconnection at one connecting point, thus enhancing the strength ofconnection. And also, it will not be easy for relative rotation of theconnected light steel keels to occur at the connecting point any longerowing to constraint of the two connecting pieces or more, thus rigidityof the structure is greatly enhanced.

Furthermore, the light steel keel connecting structure can reach veryhigh requirements on strength and stiffness, so that arranging densityof light steel keels of a light steel assembly that employs theconnecting structure can be decreased appropriately, and accordingly,the weight of material is decreased, and the cost of material isreduced. Also, the concave structure has a certain depth so that topsurfaces of connecting pieces can he wholly submerged in the concave,and accordingly, they will not cause interference to other connectingcomponents on surfaces of the light steel keels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing deformation of a light steel wallunder force that employs a light steel, keel connecting structure inprior art (a figure on the left side in FIG. 1 shows the structure ofthe light steel wall in a normal condition where no force acts on it,and a figure on the right side shows the structure of the light steelstructure after it is deformed by a force);

FIG. 2 is a schematic view showing the exploded structure of the jointof the light steel keel connecting structure according to the invention;

FIG. 2A is a structurally schematic view showing the joint of the lightsteel keel connecting structure according to the invention;

FIG. 3 is a schematic view showing an exploded structure of embodiment 1of the light steel keel connecting structure according to the invention;

FIG. 3A is a schematic view showing as connecting structure ofembodiment 1 of the light steel keel connecting structure according tothe invention;

FIG. 4 is a schematic view showing an exploded structure of embodiment 2of the light steel keel connecting structure according to the invention;

FIG. 4A is a schematic view showing a connecting structure of embodiment2 of the light steel keel connecting structure according to theinvention;

FIG. 5 is a schematic view showing an exploded structure of embodiment 3of the light steel keel connecting structure according to the invention;

FIG. 5A is a schematic view showing a connecting structure of embodiment3 of the light steel keel connecting structure according to theinvention;

FIG. 6 is a schematic view showing an exploded structure of embodiment 4of the light steel keel connecting structure according to the invention;

FIG. 6A is a schematic view showing a connecting structure of embodiment4 of the light steel keel connecting structure according to theinvention;

FIG. 7 is a schematic view showing an exploded structure of embodiment 5of the light steel keel connecting structure according to the invention;

FIG. 7A is a schematic view showing a connecting structure of embodiment5 of the light steel keel connecting structure according to theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to further illustrate the principle and structure of theinvention, preferred embodiments of the invention will now be describedin detail in conjunction with accompanied drawings.

Referring to those shown in FIG. 2 to FIG. 7A, a light steel keelconnecting structure according to the invention comprises at least twolight steel keels 1, at least two concaves and at least two connectingpieces 3.

Each of the light steel keels 1 has a connecting surface 11 connectedwith other light steel keel.

The concaves 2 are provided on connecting surfaces 11, respectively, andare depressed toward inside of the light steel keels 1 so as to form abottom surface 21, and concaves 2 on two connecting surfaces 11 that areconnected vertically are disposed by way of engagement. The opening ofthe concave 2 is slightly larger than the bottom surface 21. The shapesof bottom surfaces of two concaves 2 that are embedded vertically may beshapes of circle, cross, square, rectangle, or ring, which match witheach other vertically. When the bottom surface 21 is circle, it isunnecessary to consider an issue about direction setting, and if it hasother shape, then the direction along which up-down embedding isconducted has to be considered, and other aspects are the same as in thecase of circular shape. For the sake of illustrative convenience, thedescription will be given below only to an example in which the bottomsurface 21 is circle. A connecting hole 211 is provided on the bottomsurface 21 and the number of the connecting hole 211 within each of theconcaves 2 is at least two. Regarding connecting holes 211, they arearranged at corresponding locations of two concaves 2 that are embeddedvertically, so that two connecting holes 211 (i.e. upper and lowerconnecting holes 211) overlap upon connection.

The connecting pieces 3 may be screws, bolts or rivets, and theconnecting pieces 3 are provided within the connecting holes 211 thatoverlap with each other vertically in the state of connection. Uponsetting of the connecting holes 211 it is to be noted that the followingdimensions are ensured: after the connecting pieces 3 are inserted intothe connecting holes 211, the center distance between any two adjacentconnecting pieces 3 is not smaller than three times of the diameter ofthe connecting pieces 3, and the distance from the center of anyconnecting piece 3 to any outer edge of the light steel keel 1 is notsmaller than one and half times of the diameter of the connecting piece3. And, the set depth of the concaves 2 may be taken into account, andwhen the connecting pieces 3 are inserted, terminals (such as screwheads, bolt heads, rivet heads or the like) of the connecting pieces 3at one end where depression sides of the concaves 2 are located do notgo beyond outer edges of openings of the concaves 2 on the same side asthe terminals of the connecting pieces 3.

Embodiment 1: please refer to those shown in FIG. 3 and FIG. 3A.

In the present embodiment, the light steel keel 1 comprises a main lightsteel keel 1A and an abutting light steel keel 1H, which are connectedto each other perpendicularly.

The main light steel keel 1A comprises an upper wing plate 11A and alower wing plate 11A′, which are disposed horizontally and in parallel,and it further comprises a web 12A connected vertically between one sideof the upper wing plate 11A and one side of the lower wing plate 11A′.The upper wing plate 11A and the lower wing plate 11′ are provided witha concave 2 in symmetric positions thereof, respectively. The concave 2may be provided in the middle part of the upper wing plate 11A and thelower wing, plate 11A′.

The abutting light steel keel 1H comprises an upper wing plate 11H and alower wing plate 11H′ that are disposed horizontally and in parallel,and further comprises a web 12H connected vertically between one side ofthe upper wing plate 11H and one side of the lower wing plate 11H′. Incentral, symmetric positions, The upper wing plate 11A and the lowerwing plate 11A′ are provided with a concave 2 in symmetric positions ofmiddle part of upper wing plate 11A and the lower wing plate 11′respectively. The abutting light steel keel 1H passes through the web12A of the main light steel keel 1A vertically, and moreover, the upperwing plate 11H′ is connected to an inner side of the upper wing plate11A, and the lower wing plate 11H′ is connected to an inner side of thelower wing plate 11A′. A concave 2 on the upper wing plate 11A isembedded inside a concave 2 on the upper wing plate 11H, and a concave 2on the lower wing plate 11N is embedded inside a concave 2 on the lowerwing plate 11H′.

Two connecting holes 211 are provided on a bottom surface 21 of eachconcave 2.

The connecting holes 211 on two concaves 2, which are embeddedvertically overlap so that two fixing hole-sites are formed on each ofupper and lower wing plates.

The number of the connecting pieces 3 is four. The four connectingpieces 3 are located within the fixing hole-sites in the state ofconnection, respectively. Top surfaces of the connecting pieces 3 do notgo beyond outer surfaces of the upper wing plate 11A and the lower wingplate 11A′.

Embodiment 2: please refer to those shown in FIG. 4 and FIG. 4A.

In the present embodiment, the light steel keel 1 comprises a main lightsteel keel 1B and two abutting light steel keels 1J and 1K, which areconnected to each other perpendicularly.

The main light steel keel 1B comprises an upper wing plate 11B and alower wing plate 11B′ that are disposed horizontally and in parallel,and it further comprises a web 12B connected vertically between one sideof the upper wing plate 11B and one side of the lower wing plate 11B′.The upper wing plate 11B and the lower wing plate 11B′ are provided withtwo concaves 2 arranged in a line in symmetric positions thereof,respectively. The concaves 2 may be set in the middle part of the upperwing plate 11B and the lower wing plate 11B′.

The abutting light steel keel 1J comprises an upper wing plate 11J and alower wing plate 11J′ that are disposed horizontally and in parallel,and it further comprises a web 12J connected vertically between one sideof the upper wing plate 11J and one side of the lower wing plate 11J′.The upper wing plate 11J and the lower wing plate 11J′ at one end areprovided with a concave 2 in symmetric positions thereof respectively.

The abutting light steel keel 1K comprises an upper wing plate 11K and alower wing plate 11K′ that are disposed horizontally and in parallel,and it further comprises a web 12K connected vertically between one sideof the upper wing plate 11K and one side of the lower wing plate 11K′.The upper wing plate 11K and the lower wing plate 11K′ at one end arealso provided with a concave 2 in symmetric positions thereofrespectively.

One end of the abutting light, steel keel 1J and one end of the abuttinglight steel keel 1K are connected vertically to an inner side of themain light steel keel 1B, and moreover, the upper wing plate 11J and theupper wing plate 11K are connected to an inner side of the upper wingplate 11B, and the lower wing plate 11J′ and the lower wing plate 11K′are connected to an inner side of the lower wing plate 11B″. Twoconcaves 2 on the upper wing plate 11B are embedded inside concaves 2 onthe upper wing plate 11J and the upper wing plate 11K, respectively, andtwo concaves 2 on the lower wing plate 11B′ are embedded inside concaves2 on the lower wing plate 11J′ and the lower wing plate 11K′,respectively.

In the present embodiment, the structure of a single concave 2 is thesame as that in Embodiment 1, and repetitive descriptions are omittedhere. The number of the connecting pieces 3 is four-pair, connectingpieces 3 in each pair are disposed within two fixing hole-sites that areformed through two overlapped connecting holes 211 on two concaves,which are embedded vertically. Top surfaces of the connecting pieces 3do not go beyond outer surfaces of the upper wing plate 11B and thelower wing plate 11B′.

Embodiment 3: please refer to those shown in FIG. 5 and FIG. 5A.

The light steel keel connecting structure in the present embodimentdiffers from Embodiment 1 in that, three connecting holes 211 areprovided on the bottom surface 21 of the concave 2, and connecting holes211 on two concaves 2 that are embedded vertically overlap so as to formthree fixing hole-sites on each of upper and lower wing plates, butother parts have the same structure as that in Embodiment 1. The numberof the connecting pieces 3 is six, and the six connecting pieces 3 areprovided within the fixing hole-sites in the state of connection,respectively.

Embodiment 4: please refer to those shown in FIG. 6 and FIG. 6A.

The light steel keel connecting structure in the present embodimentdiffers from Embodiment 1 in that, four connecting holes 211 areprovided on the bottom surface 21 of the concave 2, and connecting holes211 on two concaves 2 that are embedded vertically overlap so as to formfour fixing hole-sites on each of upper and lower wing plates, but otherparts have the same structure as that in Embodiment 1. The number of theconnecting pieces 3 is eight, and the eight connecting pieces 3 providedwithin the fixing hole-sites in the state of connection, respectively.

Embodiment 5: please refer to those shown in FIG. 7 and FIG. 7A.

In the present embodiment, the light steel keel 1 comprises one mainlight steel keel 1C and three abutting light steel keels, which areconnected to each other perpendicularly. The three abutting light steelkeels are an abutting light steel keel 1H, an abutting light steel keel1M and an abutting light steel keel 1N.

The main light steel keel 1C comprises an upper wing plate 11C and alower wing plate 11C′ that are disposed horizontally and in parallel,and it further comprises a web 12C connected vertically between one sideof the upper wing plate 11C and one side of the lower wing plate 11C′.The upper wing plate 11C and the lower wing plate 11C′ are provided withthree concaves 2 arranged in a line, respectively, and the concaves 2may be provided in the middle part of the upper wing plate 11C and thelower wing plate 11C′.

The abutting light steel keel 1H has the same structure as that inembodiment 1, and repetitive descriptions are omitted here.

The abutting light steel keel 1M comprises an upper wing plate 11M and alower wing plate 11M′ that are disposed horizontally and in parallel,and it further comprises a web 12M connected vertically between one sideof the upper wing plate 11M and one side of the lower wing plate 11M′.The upper wing plate 11M and the lower wing plate 11M′ are provided witha concave 2 in symmetric positions of middle part of the upper wingplate 11M and the lower wing plate 11M′, respectively.

The abutting light steel keel 1N comprises an upper wing plate 11N and alower wing plate 11N′ that are disposed horizontally and in parallel,and it further comprises a web 12N connected vertically between one sideof the upper wing plate 11N and one side of the lower wing plate 11N′.The upper wing plate 11N and the lower wing plate 11N′ are also providedwith a concave 2 in symmetric positions of middle part of the upper wingplate 11N and the lower wing plate 11N′, respectively.

The abutting light steel keel 1H, the abutting light steel keel 1M andthe abutting light steel keel 1N pass through the web 12C of the mainlight steel keel 1C vertically, respectively, and moreover, the upperwing plate 11H, the tipper wing plate 11M and the upper wing plate 11Nare connected to an inner side of the upper wing plate 11C,respectively, and the lower wing plate 11H′, the lower wing plate 11M′and the lower wing plate 11N′ are connected to an inner side of thelower wing plate 11C, respectively. Three concaves 3 on the upper wingplate 11C are embedded inside concaves 2 on the upper wing plate 11H,the upper wing plate 11M and the upper wing plate 11N, respectively, andthree concaves 2 on the lower wing plate 11C′ are embedded insideconcaves 2 on the lower wing plate 11H′, the lower wing plate 11M′ andthe lower wing plate 11N′, respectively.

In the present embodiment, the structure of a single concave 2 is thesame as that in embodiment 1, and repetitive descriptions are omittedhere. The number of the connecting pieces 3 is six-pair, connectingpieces 3 in each pair are provided within two fixing hole-sites that areformed through overlapped connecting holes 211 on two concaves, whichare embedded vertically, and top surfaces of the connecting pieces 3 donot go beyond outer surfaces of the upper wing plate 11C and the lowerwing plate 11C′.

Here, one point should be noted, namely, the number of connecting holes211 on each concave 2 in each of above embodiments can be adjustedaccordingly in accordance with desired strength and stillness upon apractical connection and degree of size of connecting pieces 3, and isnot limited to the situations listed in the above embodiments.

At the junction of the light steel keel connecting structure of theinvention, there is provided a concave structure, for which, mechanizedmass production is implemented very easily. Positioning is extremelyeasy during assembling because concave structures of upper and lowerconnecting surfaces are embedded to each other.

Besides, two connecting pieces or more can he accommodated within theconcave structure simultaneously so that strength of connection andrigidity of light steel keels are greatly improved as well. A load willbe shared by connecting pieces because two connecting pieces or more areused for connection at one connecting junction, thus enhancing thestrength of connection, it will not be easy for relative rotation of theconnected light steel keels to occur at the connecting point any longerowing to constraint of the two connecting pieces or more, thus greatlyenhancing rigidity of the structure. Furthermore, the light steel keelconnecting structure can reach very high requirements in strength andstillness so that arranging density of light steel keels on a lightsteel assembly that employs the connecting structure can be decreasedappropriately (as seen from resultant analytical data of a designexample, the consumption of material saved by using this connectingstructure can reach 15% or more), and accordingly, the weight ofmaterial is decreased, and the cost of material is reduced. Also, theconcave structure has a certain depth so that top surfaces of connectingpieces can be wholly submerged in the concave, and accordingly, theywill not cause interference to other connecting components on surfacesof the light steel keels.

However, descriptions made above are merely preferred, feasibleembodiments, and are not construed as limiting of protection scope ofthe invention. Therefore, every equivalent change in structure, which ismade by using contents in the specification and drawings of theinvention, is embraced within the protection scope of the invention.

What is claimed is:
 1. A light steel keel connecting structure,comprising at least two light steel keels, each of which has aconnecting surface connecting with the other light steel keel, andconnecting pieces for connecting, the light steel keels, characterizedin that, concaves are provided on each of the connecting surfacesrespectively which are depressed toward inside of the light steel keels,and the concaves of two connecting surfaces which are connectedvertically are disposed by way of embedding, and at least two connectingholes are provided at corresponding positions of two concaves that areembedded, respectively, and the connecting pieces are provided withinthe connecting holes in as state of connection.
 2. The light steel keelconnecting structure according to the claim 1, characterized in that,the terminals of the connecting pieces at one end where depression sidesof the concaves are located do not go beyond outer edges of the openingsof the concaves on the same side as the terminals of the connectingpieces.
 3. The light steel keel connecting structure according to theclaim 1, characterized in that, the center distance between any twoadjacent connecting pieces is not smaller than three times of thediameter of the connecting pieces, and the distance from the center ofany of the connecting pieces to any of the outer edges of the lightsteel keels is not smaller than one and half times of the diameter ofthe connecting pieces.
 4. The light steel keel connecting structureaccording to the claim 1 characterized in that, the openings of theconcaves are slightly larger than bottom surfaces, and the connectingholes are provided on the bottom surfaces of the concaves.
 5. The lightsteel keel connecting structure according to the claim 1, characterizedin that, the shapes of bottom surfaces of the two concaves that areembedded vertically are shapes of circle, cross, square, rectangle, orring, which match to each other vertically.
 6. The light steel keelconnecting structure according to the claim 1, characterized in that,the light steel keels comprise a main light steel keel and at least oneabutting light steel keel, which are connected to each other, each ofthe main light steel keel and the abutting light steel keel comprises anupper wing plate and a lower wing plate that are disposed horizontallyand in parallel, and a web connected vertically between one side of theupper wing plate and one side of the lower wing plate, the concaves aredisposed at location where the upper wing, plate of the main light steelkeel and the upper wing plate of the abutting light steel keel areconnected and at location where the lower wing plate of the main lightsteel keel and the lower wing plate of the abutting light steel keel areconnected, and concaves on the upper and lower wing plates of the mainlight steel keel are embedded inside concaves on the upper and lowerwing plates of the abutting light steel keel, respectively.
 7. The lightsteel keel connecting structure according to the claim 6, characterizedin that, the number of the abutting, light steel keel is one, the upperand lower wing plates of the main light steel keel are provided one saidconcave in symmetric positions of the upper and lower wing plates of themain light steel keel, respectively, the upper and lower wing plates ofthe abutting light steel keel are also provided one said concave insymmetric positions of the upper and lower wing plates of the abuttinglight steel keel, respectively.
 8. The light steel keel connectingstructure according to the claim 6, characterized in that, the number ofthe abutting light steel keel is two or more, and the upper and lowerwing plates of the main light steel keel are provided with concavesarranged in a line in symmetric positions of the upper and lower wingplates of the main light steel keel, respectively, the number ofcavities is equal to the number of the abutting light steel keel, andthe upper and lower wing plates of each abutting light steel keel isprovided with one of said concave in symmetric positions of the upperand lower wing plates of each abutting light steel keel, respectively.9. The light steel keel connecting structure according to the claim 6,characterized in that, the concaves are disposed in the middle part ofthe upper and lower wing plates of the main light steel keel, one end ofthe upper wing plate of the abutting light steel keel and one end of thelower wing plate of the abutting light steel keel, and the main lightsteel keel is connected to one end of the abutting light steel keel. 10.The light steel keel connecting structure according to the claim 6,characterized in that, the concaves are disposed in the middle part ofthe upper and lower wing plates of the main light steel keel and in themiddle part of the upper and lower wing plates of the abutting lightsteel keel, the abutting light steel keel penetrates through the web ofthe main light steel keel vertically, and the middle part of the mainlight steel keel and the middle part of the abutting light steel keelare connected in the state of penetrating through vertically.